Experts providing evidence in legal cases are universally recommended to be transparent, particularlyin their reasoning,
so that legal practitioners can critically check whether the conclusions are adequately supported by the results. However,
when exploring the practical meaning of this recommendation it becomes clear that people have different things in mind. The
UK appeal court caseR v T painfully exposes the different views. In this article we argue that there can be a trade-off
between clarity and transparency, and that in some cases it is impossible for the legal practitioner to be able to followthe
expert’s reasoning in full detail because of the level of complexity. All that can be expected in these cases is that the
legal practitioner is able to understand the reasoning up to a certain level. We propose that experts should only report the
main arguments, but must make this clear and provide further details on request. Reporting guidelines should address the reasoning
in more detail. Legal practitioners and scientists should not be telling each other what to do in the setting of a legal case,
but in other settings more discussion will be beneficial to both. We see the likelihood ratio framework and Bayesian networks
as tools to promote transparency and logic. Finally, we argue that transparency requires making clear whether a conclusion
is a consensus and reporting diverging opinions on request.

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